This peripheral neuropathy predominantly affects sensory fibers of small poorly myelinated diameter (Aδ fibers and C) and autonomous sensory fibers and is called small fiber neuropathy 4. The cardinal sign of NAION is the presence of neuropathic pain but abnormalities in physical examination are often absent and conventional electromyography is faulted to make the diagnosis. These small fibers are also constituent of the autonomic nervous system and causes damage autonomic dysfunction that can manifest the cardiovascular system (hypotension, cardiac conduction disorders), digestive, sweat, sphincter. neuropathy of the diagnosis of small fibers is suggested clinically by the presence of neuropathic pain often contrasting with a normal clinical examination. The confirmation is based on electrophysiology with various techniques and quantification of intra-epidermal nerve fibers.